This invention relates to an apparatus for treating tail yarns in textile spindle assemblies of textile spinning machines, twisters or the like.
In textile spinning machines, twisters or the like equipped with auto-doffers by which the whole yarn packages mounted on the spindle assemblies are simultaneously doffed, in order to conduct automatically the doffing operation for changing the completed yarn packages to the empty bobbins, it is necessary to separate each yarn interconnecting the completed yarn package and the spindle assembly, and to pull the completed yarn packages out of the spindle assemblies, while maintaining the state in which each yarn fed from the roller part of the spinning machine is interconnected with the spindle assembly through the traveler.
For this purpose, Japanese Preliminary Patent Publication No. 60-134032/1985 proposes an apparatus comprising a base portion of a spindle on which a knurled surface is formed for fixedly wrapping a tail yarn thereon to form yarn underwindings and a cutter assembly movably mounted for separating an interconnecting yarn formed between the yarn underwindings and a portion of a bobbin where the yarn is firstly wrapped, the interconnecting yarn being separated by said cutter assembly and the yarn underwindings wrapped 4 to 5 turns on the knurled surface formed on the base portion of the spindle being cast off by rotational centrifugal force of the spindle.
According to this apparatus, however, the yarn underwindings can not be completely cast off for removal by rotational centrifugal force of the spindle. This causes further wrapping of new underwindings on the residual underwindings. As a result, the fixing effect of the yarn underwindings by the knurled surface is lost, which permits the yarn underwindings to move by a slight external force only. If it happens that the yarn underwinding move by a slight force, the yarn underwindings are loosened on rising of a ring rail to a position where the yarn is wound on the bobbin, which causes the disordered position of a traveler. Consequently, the yarn breakage is liable to occur at the start of the operation. Further the free end of the yarn underwindings is easily entangled with the yarn which is being wound on the bobbin at the re-start of the machine, which causes the yarn breakage and the occurrence of fluffs. Conventionally, in order to eliminate such inconvenience, the yarn underwindings have been periodically manually removed by use of a cutter or the like while the machine is stopped. However, such a conventional method is reduced in operation efficiency of the machine, because the operation is complex, labor intensive and time-consuming.
U.S. Pat. No. 4,208,865 discloses a clearer which separates the length of yarn interconnecting yarn underwindings with a yarn package and blow away the yarn underwindings by blasts of air. Since this clearer is actuated at the same time that the operation of the machine is initiated, the blown-away yarn underwindings are entangled with the yarn which is being wound on the bobbin, which causes yarn breakage and the occurrence of fluffs.
Further, Japanese Preliminary Paten Publication No. 60-94629/1985 discloses a method which comprises performing initial winding of a yarn on an empty bobbin to form yarn underwindings at the re-start of a machine after changing a completed yarn package to the empty bobbin, thereafter temporarily terminating the machine, pulling up the bobbin slightly from a spindle to separate a yarn interconnecting the yarn underwindings with the bobbin, putting back the bobbin in its regular position, and then starting the machine to cast off the yarn underwindings by rotational centrifugal force of the spindle. According to this method, however, the temporary termination of the machine reduces operation efficiency and yarn breakage is liable to occur at the re-start of the machine.
An object of the present invention is to solve such problems of the prior art to provide an apparatus for treating a tail yarn in which the tail yarn can be securely fixed on the base portion of the spindle and completely removed therefrom without yarn breakage and the occurrence of fluffs during operation of the machine.